Edward Snowden says FBI can hack the iPhone in the San Bernardino case Getty Images

Edward Snowden, who initially backed Apple's decision to fight a court order to help the FBI decrypt an iPhone 5C used by San Bernardino attacker Syed Farook, now says the data can be retrieved without the company's help. The former NSA contractor said the FBI can access the data using a method called "chip decapping", which involves use of acid and lasers.

"The problem is, the FBI has other means... They told the courts they didn't, but they do. The FBI does not want to do this," said Snowden through a virtual call at Johns Hopkins University from Russia where he is living in exile since fleeing the United States fearing he would be charged with leaking defence secrets.

The privacy activist has been rallying support behind Apple along with Google, WhatsApp and others who think the latest court order is a gross breach of privacy and the citizen's rights.

How decapping works

Chip decapping is a mechanism where the main processor chip of the phone is physically attacked to probe its contents. First, acid is used to remove the chip's encapsulation. After that, a laser drills down into the chip in an attempt to expose the portion of the memory that contains the iPhone's unique ID (UDID) data.

Tiny probes are then placed on the spot where the data is to read out the UDID bit by bit, as well as the algorithm used to untangle it. Once the targeted data has been extracted, the FBI can put it on a super computer and gear up to recover the missing pass code by simply trying all possible combinations until one unlocks the iPhone data. Since the process is being done outside the iOS, there is no 10-try limit or self-destruct mechanism that can wipe the data.

The major downside, however, is that if at any point there's even a slight mistake in the decapping or attack process, the chip could be destroyed and all access to the phone's memory lost forever. This may be a major reason the FBI may not be willing to take the risk to recover the data this way and rather rely on a backdoor entry via Apple.

Apple CEO Tim Cook had come down heavily on the court order to allow the FBI this kind of entry. In his latest email to his employees, he explained that the company is fighting for the privacy of all Americans and is set to file its legal response to the FBI's court order by the end of the week. Cook had earlier said he wanted the government to drop the order and let a federal commission decide.

The FBI has argued the data is crucial for them to establish possible links between Farook and his wife Tashfeen Malik to the Islamic State (Isis) in relation to the San Bernardino attack which killed 14 people and injured 22 others. Relatives and victims of the attack have also sided with the FBI against Apple pleading that security and justice were greater concerns than privacy.